Method of making textile yarns

ABSTRACT

A compact yarn of staple fibres containing at least a proportion of potentially adhesive fibres bonded to contacting fibres. The compact yarn may be made by false twisting a sliver of the staple fibres by means of a fluid vortex followed by activating the potentially adhesive fibres.

United States Patent 1 Selwood 1 July 17, 1973 METHOD OF MAKING TEXTILEYARNS [75] Inventor: I Alan Selwood, Allt-yr-Yn, Newport,

England I [73] Assignee: Imperial Chemical Industries Limited, London,England [22] Filed: May 10, 1971 {21] Appl. No.: 141,713

[30] Foreign Application Priority Data May 20, 1970 Great Britain24,421/70 [52] US. Cl 57/157 R, 57/157 MS [51] int. Cl D02g 3/00 [58]Field of Search 57/34 R, 34 B, 140 C,

57/140 R, 140 BY, 157 R, 157 F, 157-MS, 157 TS, 153, 164, 162;161/172-181 [56] References Cited UNITED STATES PATENTS 3,439,491 4/1969Scruggs 57/140 BY 3,468,746 9/1969 Scheier 1. 57/140 BY 3,483,57012/1969 Fisher 57/153 X 3,490,219 l/l970 Ozawa et al. 57/140 R 3,616,16710/1971 Gosden 57/140 BY 3,624,999 12/1971 Young 57/153 PrimaryExaminer-Werner H. Schroeder Attorney-Cushman, Darby & Cushman 57ABSTRACT A compact yarn of staple fibres containing at least aproportion of potentially adhesive fibres bonded to contacting fibres.The compact yarn may be made by false twisting a sliver of the staplefibres by means of a fluid vortex followed by activating the potentiallyadhesive fibres.

11 Claims, 2 Drawing Figures 1 METHOD OF MAKING TEXTILE YARNS Thisinvention concerns improvements in or relating to the production ofcompact yarns and tows from discontinuous fibres.

By a compact yarn we mean that the fibres are bound together such thatthe yarn is manipulatable an an entity.

Conventionally, bundles of stable fibres have been rendered compact bythe insertion of a high level of twist. The capabilities oftwist-inserting agencies have limited the rate of yarn production and ithas long been be gained from the use of substantially twistless yarnsprovided these can be handled in subsequent textile processes such asweaving. In addition, substantially twistless yarns can add structureand textural characteristics to fabrics. Further, in fabrics knitted orwoven from conventional staple fibre yarns, fibres are pulled out fromthe surface and often tend to form small balls on the surface of thefabric, this effect is referred to as pilling. The compact yarns of thepresent invention show a reduced tendency to pilling.

Accordingly, the present invention provides a compact yarn comprising anessentially parallel assembly of discontinuous fibres, consisting of atleast a proportion of potentially adhesive fibres, said adhesive fibresbeing bonded to contacting fibres such that the bonded yarn has anaverage stripping force as defined of at least l.0 g, a tenacity ofat-least 0.5 g/dtex and a yarn stiffness as defined of less than 0.005.

The present invention also provides a process for producing a compactyarn comprising false-twisting a sliver of discontinuous fibres,consisting of at least a proportion of potentially adhesive fibres, andsubsequently activating the potentially adhesive fibres so as to bondthem to contacting fibres.

By a sliver we mean an essentially parallel assembly of fibressubstantially without twist.

Stripping force is defined as the force required to remove a singlefibre from a bonded yarn and is measured by clamping one end of the yarnin the top jaws of an lnstron Tensile Tester and a free fibre end,teased from the yarn, in the lower jaws which are then lowered at a rateof 5 cm/min. The force, in grams, to break or withdraw the fibre fromthe yarn is the stripping force. The average of tests is taken.

Yarn stiffness is defined as follows: A circular loop of the yarn 6.2cms in diameter is hung on a horizontal cylindrical pin 0.64 ems indiameter. A weight of 0.05 g is suspended from the bottom of loop, andthe maximum horizontal diameter of the resulting deformed loop (D cms)is measured. The linear density of the yarn is measured in Tex (A). Theyarn stifiness, X, is calculated where X D 0.64/A2. It is preferred thatthe bonded yarn has an average stripping force of at least. 3.0 g. It isfurther preferred that the bonded yarn has a yarn stiffness less than0.003. 4

Activation of the potentially adhesive fibres, i.e., rendering thefibres temporarily adhesive, may be achieved by heat or by chemicaltreatment depending on the nature of the fibres.

In one embodiment of the invention, activation of thepotentiallyadhesive fibres is carried out intermittently, for example,by wrapping the sliver of discontinuous fibres around a heated groovedroll. Activation may i I recognised that there are advantages ofproductivity to ethylene also be achieved by using a heated fluid suchas, for example, air or steam.

The discontinuous fibres may consist wholly of potentially adhesivecomposite fibres or alternatively may comprise a mixture of non-adhesivefibres and potentially adhesive homofibres or composite fibres.

The composite fibres must contain a potentially adhesive component,i.e., a component capable of being rendered temporarily adhesive. Thecomponents of the composite fibre may be arranged side-by-side or onecomponent may be completely surrounded by another component, i.e., in asheath and core relationship with, for example, the component formingthe sheath being the potentially adhesive component, or the compositefibre may be of non-circular form, for example, trilobal with one ormore of the lobes being formed at least in part by the potentiallyadhesive component. Examples of suitable composite fibres arepoly(epsilon caprolactam)/ poly(hexamethylene adipamide) fibres, poly-(ethylene terephthalate-ethylene adipate)/poly(ethylene terephthalate),poly(ethylene terephthalateisophthalate)/poly(ethylene terephthalate)fibres, the first mentioned component being the potentially adhesivecomponent.

Examples of potentially adhesive homofibres which may be employed inadmixture with non-adhesive fibres are poly(epsilon caprolactam) andpolypropylene fibres.

By non-adhesive fibres is meant fibres which are not rendered adhesiveby the activation treatment. The non-adhesive fibres may comprisesynthetic fibres such as, for example, poly(ethylene terephthalate),poly(- hexamethylene adipamide) or polyacrylonitrile fibres or naturalfibres or may comprise a mixture of fibres.

The mixture of non-adhesive fibres and potentially adhesive fibres maybe obtained by any known blending technique. It is preferred that thepotentially adhesive fibres comprise 5 to 25 percent by weight on theweight of the mixture of fibres.

The sliver is preferably false-twisted by means of a fluid vortex and itis further preferred that the sliver be heated during its passagethrough the vortex by supplying fluid at an elevated temperature.

One embodiment of the invention will now be described with reference tothe accompanying drawings, in which FIG. 1 is a schematic side view ofone embodiment of the process of the invention,

FIG. 2 is a sectional view of the fluid vortex jet shown in FIG. 1.

Referring to FIG. 1, there is shown a sliver 1 of staple fibrescontaining potentially adhesive fibres passing through the front rolls3,5 of a conventional apron drafting system. The drafted sliver issucked into a fluid vortex jet 7 supplied with heated air via inlet tube9. The fluid jet twists the sliver into yarn in the region between thevortex jet 7 and the nip of the drafting rolls 3,5. The length of thisregion is less than the length of the staple fibres comprising sliver 1.

The fluid vortex jet 7 is shown in detail in FIG. 2. It comprises aninsert member 25 and a body member 33.

The insert member 25 has an annular passage, providing an induction end23, a locating shoulder 27 and a helical thread 29. The body member 33has an annular passage 35 and is provided with a fluid inlet tube 9. Theinsert member 25 and the body member 33 are threadably joined at 31 andlocated by means of shoulder 27.

In operation, fluid is forced into the jet via inlet tube 9. The fluidimpinges on helical thread 29 with the result that a fluid vortex isestablished in passage 35. Drafted sliver is sucked into the jet viainduction end 23 and is twisted in passage 35 by means of the fluidvortex.

The invention is illustrated but not limited by the following examplesin which parts and percentages are by weight:

Example 1 This illustrates the preparation of a compact yarn from ablend of poly(epsilon caprolactam) (nylon 6) fibres andpoly(hexamethylene adipamide) (nylon 6.6) fibres.

Three parts of 2.1 dtex d.p.f., 1.4 inches long nylon 6 fibres and sevenparts of 1.7 dtex d.p.f., 1.5 inches long nylon 6.6 fibres were blendedby carding three times and drafting twice to give a sliver.

The sliver was drafted on a conventional two stage apron draft with atotal nominal draft of 26. The front rolls, rotating at acircumferential speed of approximately 100 f.p.m. After passing threetimes over the hot roll and an associated separator roll, the yarn waswound up on a cheese at approximately 100 f.p.m.

The air vortex tube was 3% inches long, the insert was 1% inches longand 1 3/16 inch diameter, with a tubular passageway of H16 inch diameterbore down the centre. The helical thread on the outside of the insertwas 3/ 16 inch long, measured along a line parallel to the axes of theinsert. The clearance between the threaded portion of the insert andtube in which it is inserted was 0.001 inches.

It was supplied with 14 litres of air per minute at a pressure of 17p.s.i. and a temperature of 155 C.

The surface of the hot roll had axially extending grooves /4 inch wideseparated by lands )4; inch wide cut across half the width of the roll.The yarn was heated by wrapping it once around the smooth part of theroll and segmentally bonded by wrapping it twice around the landed partof the roll. The hot roll temperature was approximately 250 C.

A compact yarn with the following properties was obtained: denier 432,tenacity 1.5 g.p.d. and extensibility percent.

Example 2 A sliver was made as in Example 1 from a blend of 70 percentof 3.3 dtex d.p.f., 1% inches long poly(ethylene terephthalate) staplefibres and 30 percent of 3.3 dtex d.p.f., 1% inches long sheath-corecomposite fibres having a core to sheath weight ratio of 2 to 1. Thecore comprised poly(ethylene terephthalate) and the sheath comprised acopolymer consisting of 80 percent of ethylene terephthalate units and20 percent of ethylene isophthalate units.

The sliver was drafted at a draft of 25, compacted in a fluid vortextube by air fed at 15 litres per minute at a temperature of 150 C andthen bonded by wrapping it 3 times around the grooved part of a heatedgrooved roll and associated separator roll as in Example 1. The heatedroll had a surface temperature of 250 C.

A compact yarn having the following properties was obtained: denier 444,tenacity 1.6 g.p.d., extensibility 17.5 percent and initial modulus 26g.p.d.

Example 3 Three slivers were made from blends of fibres containingrespectively, percent; percent; percent of 3.3 dtex per filament 38 mmpolyethylene terephthalate fibres; and 20, 10 and 5 percent of abicomponent fibre with a core of polyethylene terephthalate and a sheathof a copolymer comprising 20 mole percent polyethylene adipate and 80percent polyethylene terephthalate. The weight ratio of core to sheathwas 2 to l. These slivers were drafted 20 times to give a yarn of 20scotton count at feet per minute, compacted in a fluid vortex tube as inExample 1 and bonded by wrapping seven times round a separator roll andhot roll, with a surface temperature of about 265 C. The resulting yarnshad tenacities of 1.5; 1.1 A 0.3 g/dtex respectively, average strippingforces of 8.3, 10.2 and 3.9 g respectively and yarn stiffnesses of0.0032, 0.0044 and 0.0019 respectively.

Example 4 A sliver was made from 3.3 dtex per filament 38 mm long coresheath bicomponent fibres. The core was made of 6.6 nylon and the sheathof 6 nylon. The weight ratio of core to sheath was 2 to 1. The sliverwas drafter and compacted as in Example 1 and then bonded by wrappingonce round the smooth part of the heated roll and twice round thegrooved part. The peripheral speed of the hot roll was 100 feet/min andthe surface temperature about 240 C. A compact yarn of followingproperties was obtained: Linear density 390 dtex, tenacity 1.4 g perdtex, extensibility 20 percent, initial modulus 7 g per dtex, averagestripping force 7.3 g and yarn stifiness 0.0011.

Example 5 A roving of 2 cotton count was made by conventional means froma blend of fibres comprising 30 percent cotton, 30 percent nylon 6.6 38mm long 1.7 dtex, 40 percent bicomponent fibre with nylon 6.6 core andnylon 6 sheath 38 mm long 3.3 dtex. The weight ratio of core to sheathwas 2 to 1. The roving was drafted approximately 20 times with the frontrollers of the drafting system running at 300 feet per minute. Aftercompacting in an air vortex false twister as in Example 1, the yarn wasbonded by passing eight times round a heated roll with a surfacetemperature about 265 C. The yarn had an average stripping force of 1.2g, a yarn stiffness of 0.0006 and a tenacity of 0.9 g/dtex. The yarn waswoven into fabric which was of good even appearance and which showedgood resistance to pilling.

Example 6 A sliver was made from a blend of 50 percent nylon 6.6 and 50percent of a side/side bicomponent fibre of nylon 6 and nylon 6.6. Thesliver was drafted to 200 dtex yarn at 100 feet/min, compacted in an airvortex as in Example 1 and bonded by means of a heated roll with surfacetemperatures of 250 C. The resulting yarn had a tenacity of 1.3 g/dtex.

Example 7 A blend comprising 60 percent polyester terephthalate and 40percent of a 2:1 by weight corezsheath bicomponent fibre withpolyethylene terephthalate core and a copolymer of 80 percentpolyethylene terephthalate percent polyethylene isophthalate as sheath,was made into a sliver and drafted times at 100 feet/min and thencompacted in an air vortex false twister as in Example 1. Part of theyarn was bonded by passing over a partly grooved hot roll (9% inch widegrooves separated by l/32 inch wide lands for half the Example 8 Aroving comprising 70 percent 1.7 dtex 38 mm polyethylene terephthalatefibres and percent of the bi-' component fibre used in Example 7 wasdrafted to 158 dtex at 300 feet/min and passed into an air vortex. Airwas supplied to the vortex at pressures of 20, 40 and 60 p.s.i. and attemperatures from 90 to 260 C. On leaving the vortex the yarns werebonded with 5 wraps round a heated roll at about 260 C. There was littledifference in the properties of the yarn with changes in vortexconditions. At pressures below 20 p.s.i. there was insufficient suck forfibres to enter the vortex. The yarns had average stripping forces of4.8 g, and yarn stiflnesses of 0.0043. and tenacities of 1.5 g/dtex.

Example 9 A roving of two cotton count linear density was prepared byconventional means. This roving contained 33 percent by weight cottonfibres, 37 percent 1.7 dtex 38 mm polyethylene terephthalate fibres and30 percent 3.3 dtex 38 mm bicomponent core-sheath (weight ratio 2:1)fibre with polyethylene terephthalate core and 20 percent polyethyleneisophthalate 80 percent polyeth ylene terephthalate sheath. The rovingwas drafted to a nominal draft of 20. The front rolls of the draftingmachine were rotating at about 160 feet per minute surface speed. Afterthe tissue of fibres was compacted in an air vortex supplied with air at175 C, the yarn was passed over the heated grooved roll and associatedseparate roll of Example 7, one wrap round the smooth part of the rolland three round the grooved part. The surface temperature of the rollwas at about 250 C. The bonded yarn was wound up on a surface driventube at about 155 feet per minute.

The yarn had an average stripping force of 4.1 g, (4.0 3 after boilingin water), a yarn stiffness of 0.0023, an average linear density of 37%cotton count, tenacity of 0.91 g/dtex (unchanged after boiling in water)and extensibility of 8.7 percent, and was subsequently woven into aplain weave fabric having 112 ends per inch and 68 picks/inch. Thisfabric was of good appearance, and had better covering power than asimilar fabric woven from a 33 percent cotton 67 percent polyethyleneterephthalate ring spun yarn of similar count. The pilling propensity ofthe fabrics were compared using the following pilling test:

Four samples, 4% inches X 5% inches in size, of each fabric were wrappedround rubber tubes about 1 inch in diameter and 6% inches long. Thesamples were tumbled in a cuboid shaped box of about 9 inches sidelength, lined with cork, for a period of 5 hours. The samples wereinspected at intervals and any occurrence of pilling noted.

The fabric from yarn produced according to the present invention pilledless than the fabric from the ring spun yarn.

Example 10 A roving containing 30 percent of the bicomponent fibre usedin Example 9 and 70 percent of 3.3 dtex 38 mm polyethylene terephthalatewas drafted and the issuing tissue of fibres compacted in the air vortexfed with air at a temperature of 200 C, the unbonded yarn was wound upat 200 feet per min.

A package of this yarn was placed in a circulating air oven whosetemperature was controlled at 215 C. The yarn was removed 30 minuteslater and when tested had a tenacity of 1.4 g/dtex, an average strippingforce of 8.9 g'and a yarn stiffness of 0.0090; before placing in theoven the yarn had been too weak to test.

Example 1 1 A double sided hot plate 25 mm wide and 160 mm long and 18%mm thick was made. At each end of this plate rollers of 19 mm diameterwere mounted and provided with rotating means. Yarns could be passedsev' eral times round the plate, and roller without the main bulk of theyarn being in contact with the plate. A roving similar to that inExample 10 except the polyethylene terephthalate was of 1.7 dtex wasdrafted at 100 feet/min and compacted in an air vortex, the yarn wasthen wrapped 5 times round the hot plate roller system described abovewith the rollers driven at 100 feet/min surface speed. Thetemperaturesof the hot plate varied from about 250 to 270 C along itslength. The result ing yarn had a tenacity of 1.7 g/dtex, an averagestripping force of 7.3 g and a yarn stiffness of 0.0085.

Example 12 A yarn was made as in Example 9 except that the fibre blendcontained 67 percent of the bicomponent fibre and no polyethyleneterephthalate fibre. The yarn had an average stripping force of 3.2 g, atenacity of l .0 g/dtex and a yarn stiffness of 0.0076. The yarn waswoven in the same way as in Example 9 but the resulting fabric had aharsh, papery handle.

I claim:

1. A process for producing a compact yarn from a sliver comprisingdiscontinuous fibers, at least a pro portion of said discontinuousfibers consisting of potentially adhesive fibers, the process comprisingforwarding a sliver from feed means to a fluid false twisting zone suchthat the whole sliver is false twisted in said zone under asubstantially zerojtension, subsequently activating the potentiallyadhesive fibers so as to bond them to contacting fibers in said sliver,and collecting the compact yarn.

2. A process according to claim 11 in which the sliver of discontinuousfibres is false twisted by passing it through a fluid vortex.

3. A process according to claim 2 in which the fluid vortex is suppliedwith fluid at a temperature within the range to 260 C inclusive.

4. A process according to claim 2 in which the potentially adhesivefibres are activated by heat.

5. A process according to claim 2 in which the potentially adhesivefibres are activated by chemical treatment.

6. A process according to claim 2 in which the potentially adhesivefibres are activated intermittently along their length.

7. A process for producing a compact yarn from a moving slivercomprising subjecting a sliver mixture of 75-95 percent of non-adhesivefibers and 5-25 percent adhesive fibers to false-twisting by means of afluid supplied to a fluid vortex at an elevated temperature andthereafter activating the adhesive fibers to efi'ect bonding of saidfiber mixture into a compact yarn.

8. The process of claim 7 wherein the fluid in the fluid vortex is hotair or steam and the activation of the adhesive fibers is effected byheat.

9. The process of claim 8 wherein the fluid is hot air at a temperatureof at least C and the activating temperature of the adhesive fibers isat least 250 C.

10. The process of claim 7 wherein the adhesive fibers are compositefibers the components being arranged in a side-by-side or sheath andcore relationship.

ll. The process of claim 7 wherein the fluid in the fluid vortex is hotair or steam and the activation of the adhesive fibers is effected bychemical means.

# i i t i

2. A process according to claim 1 in which the sliver of discontinuousfibres is false twisted by passing it through a fluid vortex.
 3. Aprocess according to claim 2 in which the fluid vortex is supplied withfluid at a temperature within the range 90* to 260* C inclusive.
 4. Aprocess according to claim 2 in which the potentially adhesive fibresare activated by heat.
 5. A process according to claim 2 in which thepotentially adhesive fibres are activated by chemical treatment.
 6. Aprocess according to claim 2 in which the potentially adhesive fibresare activated intermittently along their length.
 7. A process forproducing a compact yarn from a moving sliver comprising subjecting asliver mixture of 75-95 percent of non-adhesive fibers and 5-25 percentadhesive fibers to false-twisting by means of a fluid supplied to afluid vortex at an elevated temperature and thereafter activating theadhesive fibers to effect bonding of said fiber mixture into a compactyarn.
 8. The process of claim 7 wherein the fluid in the fluid vortex ishot air or steam and the activation of the adhesive fibers is effectedby heat.
 9. The process of claim 8 wherein the fluid is hot air at atemperature of at least 150* C and the activating temperature of theadhesive fibers is at least 250* C.
 10. The process of claim 7 whereinthe adhesive fibers are composite fibers the components being arrangedin a side-by-side or sheath and core relationship.
 11. The process ofclaim 7 wherein the fluid in the fluid vortex is hot air or steam andthe activation of the adhesive fibers is effected by chemical means.